Experts have found further evidence that cholesterol-lowering drugs can help protect against Alzheimer’s disease. Researchers in the US said they had uncovered the first direct evidence that statins - used by three million people in Britain - could ward off the illness.

A large-scale study by Boston University found the drugs may cut the risk of Alzheimer’s by as much as 79 per cent, even in people believed to be genetically predisposed to the disease.

The lead author of the study, Dr Gail Li, said hers was the first to compare the brains of people who had received statins with those who had not. The assistant professor of psychiatry and behavioural sciences at the University of Washington School of Medicine in Seattle and her colleagues examined the brains of 110 people. They were aged 65 to 79 and had donated their brains for research. The two changes in the brain considered the most definitive hallmarks of Alzheimer’s are called brain “plaques” and “tangles”. These are protein deposits that appear to spread in the brain, although the exact cause of Alzheimer’s is not fully understood.